The use of botulinum toxin type‐B in the treatment of patients who have become unresponsive to botulinum toxin type‐A – initial experiences

The increasing use of botulinum toxin type‐A, especially for focal dystonia and spasticity has highlighted the issue of secondary non‐responsiveness. Within the last few years botulinum toxin type‐B (Myobloc®/Neurobloc®) has become commercially available as an alternative to type‐A. This paper discusses our initial experience of botulinum toxin type‐B in a total of 63 individuals who attended our botulinum clinic. Thirty‐six patients had cervical dystonia and a secondary non‐response to type‐A toxin. Thirteen of these patients (36%) had a reasonable clinical response to Neurobloc® and continue to have injections. The other 23 patients either had no response, or a poor response, or had unacceptable side effects and ceased treatment. A small number of people with blepharospasm, hemifacial spasm and foot dystonia also had a disappointing response to injection. Twenty patients with spasticity were also type‐A resistant. Seven of these show some continuing response to type‐B, without unacceptable side effects. These findings demonstrate that botulinum toxin type‐B has a place in the management of patients who have become non‐responsive to type‐A, but overall the responses to type‐B toxin were disappointing.